EvanFlow – A TDD driven feedback loop for Claude Code

A TDD-driven iterative feedback loop for software development with Claude Code. 16 cohesive skills + 2 custom subagents walk an idea from brainstorm through implementation, with checkpoints throughout where you stay in control. One entry point: say "let's evanflow this" and the orchestrator runs the loop. brainstorm → plan → execute (sequential or parallel) → tdd → iterate → STOP The loop is conductor, not autopilot: real checkpoints at design approval, plan approval, and after iteration. The agent stops short of every git operation and waits for your direction. No auto-commits. No forced ceremony. No "must invoke a skill" tax. The recommended path — Claude Code's plugin marketplace: /plugin marketplace add evanklem/evanflow /plugin install evanflow@evanflow Restart, then try: "Let's evanflow this — I want to add a small feature that does X." evanflow-go fires and walks the loop. The git-guardrails hook auto-activates with the plugin (no settings.json edit needed). Skills appear under the evanflow: namespace (e.g., /evanflow:evanflow-go ). See Installation below for two alternative paths. The loop is built around discipline that compounds across iterations, not single-shot generation. Every step has a checkpoint that gates the next: - Brainstorm clarifies intent, proposes 2–3 approaches with embedded grill (stress-test) → you approve the design - Plan maps file structure first (deep modules, deletion test) → you approve the plan - Execute runs task-by-task with inline verification → blockers stop the loop and surface to you - TDD is vertical-slice only: one failing test → minimal impl → repeat. Tests verify behavior through public interfaces, so they survive refactors - Iterate re-reads the diff with fresh eyes, runs quality checks, screenshots UI changes, and runs against a Five Failure Modes checklist (hallucinated actions, scope creep, cascading errors, context loss, tool misuse). Hard cap of 5 iterations - STOP. Report. Await your direction. The agent never auto-commits, never auto-stages, never proposes a PR For plans with 3+ truly independent units, the loop forks into a parallel coder/overseer orchestration: one coder per unit (using vertical-slice TDD with a RED checkpoint), one overseer per coder (read-only review subagent that can't modify code), plus an integration overseer that runs named integration tests at every touchpoint. The integration tests are the executable contract — interfaces can't drift if both sides have to satisfy the same passing test. Several rules come from 2025-2026 industry research on agentic coding failure modes and are baked into every skill: - Never invent values — file paths, env vars, IDs, function names, library APIs. If unsure, the agent stops and asks. (Action-hallucination is the most dangerous agent failure.) - Assertion-correctness warning — research shows 62% of LLM-generated test assertions are wrong. Both evanflow-tdd and the overseer review explicitly check whether a one-character bug in the implementation would still let the assertion pass. - Watch for context drift — evanflow-compact triggers when symptoms appear (re-asking established questions, contradicting earlier decisions). Industry data: ~65% of enterprise AI coding failures trace to context drift, not raw token exhaustion. - Five Failure Modes pass in iterate + overseer review — explicit check against hallucinated actions, scope creep, cascading errors, context loss, tool misuse. - No skill tax — ad-hoc questions don't require a skill invocation. Skills are tools, not a tollbooth. | Skill | Purpose | |---|---| evanflow-brainstorming | Clarify intent, propose 2–3 approaches with embedded grill (stress-test). Mockup quick-mode for visual-only requests. | evanflow-writing-plans | File structure first, bite-sized tasks, embedded grill. Step 2.5 offers evanflow-coder-overseer if the plan is parallelizable. | evanflow-executing-plans | Task-by-task with inline verification. Step 0 re-offers parallel path. Hands off to iterate, then STOPS. | evanflow-tdd | Vertical-slice TDD. One test → one impl → repeat. Behavior through public interface. Assertion-correctness warning. | evanflow-iterate | Self-review loop after implementation. Re-read diff, fix issues, run quality checks, screenshot UI (via headless Chromium). Five Failure Modes checklist. Hard cap of 5 iterations. | | Skill | Purpose | |---|---| evanflow-go | Single entry point. Say "let's evanflow this" and it walks the whole loop. | evanflow-glossary | Extract canonical domain terms into CONTEXT.md . Flag ambiguities and synonyms. | evanflow-improve-architecture | Surface refactor opportunities via the deletion test + deep-modules vocabulary. | evanflow-design-interface | "Design it twice" — spawn 3+ parallel sub-agents with radically different constraints, compare on depth/simplicity/efficiency. | evanflow-debug | Root-cause discipline. Hypothesis stated explicitly, embedded grill before fixing, failing test first. | evanflow-review | Both halves of code review (giving + receiving). Don't capitulate to feedback you can't justify. | evanflow-prd | Synthesize a PRD from existing context. For substantial new features. | evanflow-qa | Conversational bug discovery → issue draft. Asks before filing. | | Skill | Purpose | |---|---| evanflow-compact | Long-session context management. Strategies for proactive summarization at clean boundaries. Drift symptoms checklist. | | Skill | Purpose | |---|---| evanflow | The index. Shared vocabulary + when to invoke each evanflow-* skill. | In agents/ — invoked via Agent tool with subagent_type: parameter: | Subagent | Tool restrictions | Purpose | |---|---|---| evanflow-coder | Read, Edit, Write, Glob, Grep, Bash, TodoWrite | Implementation subagent for evanflow-coder-overseer . Tools + system prompt prevent git ops, out-of-scope edits, value hallucination. | evanflow-overseer | Read, Grep, Glob (no Edit/Write/Bash) | Read-only review subagent. Tools physically enforce "report findings, never fix." | hooks/block-dangerous-git.sh — PreToolUse hook that blocks destructive git ops (git push , git reset --hard , git clean -f , git branch -D , git checkout . , git restore . ). Auto-activates with the plugin install path. - Never auto-commit, never auto-stage, never auto-finish. Every git write op requires you to explicitly ask in the current turn. - Never invent values. File paths, env vars, IDs, function names, library APIs — if unsure, the agent stops and asks. - No skill tax. Ad-hoc questions don't require a skill invocation. Skills are tools, not a tollbooth. - No forced spec/plan paths. Files live where you want them. - Verify before claiming done. Quality checks (typecheck, lint, test) run before any "done" report. - Claude Code (any recent version) - Bash — for the bundled hook script (Linux, macOS, or Windows + WSL) jq — used by the hook script to parse Claude's JSON tool input. Install viaapt install jq ,brew install jq , or your platform's package manager. Ifjq is missing, the guardrail hook fails silently and dangerous git ops are NOT blocked. Optional but recommended: chromium orgoogle-chrome — forevanflow-iterate 's visual verification of UI changes (chromium --headless --screenshot=... ). Falls back gracefully if missing — the skill flags it and asks you to verify visually. Three paths, in priority order. All three end with the same skill set in your .claude/skills/ . The plugin path additionally auto-wires the guardrail hook. This is the cleanest install. Skills, agents, AND the guardrail hook all activate automatically. /plugin marketplace add evanklem/evanflow /plugin install evanflow@evanflow Restart Claude Code (or /reload-plugins ). Skills appear namespaced as /evanflow:evanflow-go , /evanflow:evanflow-tdd , etc. Auto-invocation via "let's evanflow this" still works regardless of namespace. To uninstall: /plugin uninstall evanflow@evanflow . Works against any GitHub repo with SKILL.md -shaped folders. Installs skills only — does not install the guardrail hook or custom subagents (you'd add those manually if you want them). # Install all 16 skills at once npx skills@latest add evanklem/evanflow -s '*' -y # Or install individual skills npx skills@latest add evanklem/evanflow/evanflow-go npx skills@latest add evanklem/evanflow/evanflow-tdd # ... This places skills under ~/.claude/skills/ (global) or .claude/skills/ (project, auto-detected). For users who want full control, no CLI dependencies. git clone https://github.com/evanklem/evanflow.git cd evanflow # Skills (project-level — adjust to ~/.claude/skills/ for global) mkdir -p .claude/skills cp -r skills/* .claude/skills/ # Agents (custom subagents used by evanflow-coder-overseer) mkdir -p .claude/agents cp agents/*.md .claude/agents/ # Git guardrails hook (optional but recommended) mkdir -p .claude/hooks cp hooks/block-dangerous-git.sh .claude/hooks/ chmod +x .claude/hooks/block-dangerous-git.sh Then register the hook in your .claude/settings.json : { "hooks": { "PreToolUse": [ { "matcher": "Bash", "hooks": [ { "type": "command", "command": "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/block-dangerous-git.sh" } ] } ] } } Optionally, paste examples/CLAUDE.md.snippet into your project's CLAUDE.md to brief Claude about EvanFlow's conventions. Restart Claude Code. Try saying: "Let's evanflow this — I want to add a small feature that does X." evanflow-go should fire and walk you through the loop. To verify the guardrail hook (paths 1 and 3 only): try git reset --hard HEAD from the Bash tool — it should be blocked with "BLOCKED: ... matches dangerous pattern". Every skill has a clear structure with a ## Hard Rules section. To adapt to your project: - Replace and placeholders in skills likeevanflow-writing-plans with your actual paths if you find yourself answering the same question repeatedly. - Document your project's quality checks in your CLAUDE.md — exacttypecheck ,lint , andtest commands. The skills reference these abstractly. - Adapt the visual verification step in evanflow-iterate if you don't havechromium available — substitutegoogle-chrome --headless or another tool. - Edit the cohesion contract template in evanflow-coder-overseer to match your project's conventions (your authentication middleware name, your DB write helper, etc.). The skills are designed to be edited. Treat them as starting points, not gospel. If you fork to make a vendor-specific variant (your-name-flow), great — that's the spirit. You say: "let's evanflow this — I want to add a feature that does X" │ ▼ evanflow-go (the conductor) │ ├─ Phase 0: Restate idea, scope check ├─ Phase 1: evanflow-brainstorming (CHECKPOINT: design approval) ├─ Phase 2: evanflow-writing-plans (CHECKPOINT: plan approval) │ └─ Step 2.5: parallelization check ├─ Phase 3: evanflow-executing-plans (sequential) │ OR │ evanflow-coder-overseer (parallel) │ ├─ contract with named tests + integration tests │ ├─ RED checkpoint (all coders write failing tests, orchestrator verifies) │ ├─ GREEN phase (vertical-slice TDD per coder) │ ├─ per-coder overseers (review, never fix) │ └─ integration overseer (runs touchpoint tests) ├─ Phase 4: evanflow-iterate (5x cap, Five Failure Modes pass) └─ Phase 5: STOP. Report what was done. Await your direction. Cross-cutting: evanflow-compact runs at clean boundaries when context gets heavy. Special-purpose skills (evanflow-debug , evanflow-improve-architecture , evanflow-design-interface , evanflow-glossary , evanflow-prd , evanflow-qa , evanflow-review ) are pulled in mid-flow when relevant. . ├── .claude-plugin/ │ ├── plugin.json — plugin identity (name, description, version) │ └── marketplace.json — marketplace manifest (lists EvanFlow as one bundled plugin) ├── skills/ — 16 SKILL.md folders │ ├── evanflow/ │ ├── evanflow-go/ │ ├── evanflow-brainstorming/ │ ... (etc) ├── agents/ — 2 custom subagent definitions │ ├── evanflow-coder.md │ └── evanflow-overseer.md ├── hooks/ │ ├── hooks.json — auto-activated when plugin installs │ └── block-dangerous-git.sh ├── examples/ │ └── CLAUDE.md.snippet — for the manual-copy install path ├── docs/ │ └── skills-audit.md — verdict on all 38 candidate skills considered ├── README.md └── LICENSE — MIT EvanFlow synthesizes ideas from: - mattpocock/skills by Matt Pocock — vertical-slice TDD, deep modules, deletion test, design-it-twice, ubiquitous language, grill-me, caveman. - superpowers by Jesse Vincent — verification-before-completion, code review patterns, parallel agent dispatch, finishing-a-development-branch (the 4-option presentation). - git-guardrails-claude-code — bundled in hooks/ (script copied verbatim). Original by Matt Pocock. Industry research informing the design: - Anthropic's 2026 Agentic Coding Trends Report - 9 Critical Failure Patterns of Coding Agents (DAPLab, Columbia) - Test-Driven Development for Code Generation (arXiv 2402.13521) — assertion-correctness findings MIT. See LICENSE. Issues and pull requests welcome. EvanFlow is opinionated by design — proposals to add ceremony or auto-actions will be politely declined. Proposals to further reduce ceremony, sharpen rules, or add evidence-backed improvements are very welcome.